Radio broadcast .. (1922-30)

RADIO BROADCAST JANUARY, 1929 KEITH HENNEY Director of the Laboratory WILLIS KINGSLEY WING, Editor EDGAR H. FELIX Contributing Editor HOWARD E. RHODES Technical Editor Vol. XIV. No. 3 Cover Design - - - From a Design by Harvey Hopkins Dunn Frontispiece - A Kite Antenna Used in Early Radio Experiments Unscrambling Television ...... Boyd Phelps All About the Dynamic Loud Speaker - Joseph Morgan Book Review - - - - - - - Carl Dreher The March of Radio - 1 56 157 159 162 WGY'S Attack on the Allocation Plan Ira E. Robinson Stands Firm The Regenerative Decision An Editorial Interpretation 163 With the Broadcasting Stations Commercial Radio Telegraphy With the Radio Manufacturer A Few Radio Questions Answered Measuring a Receiver's Performance "Strays" from the Laboratory How Much Power Is Needed? What is a Dynamic Speaker Some Interesting Formulas Obtaining C Bias The Task of Editing Empirical Rules and Formulas - - 166 Kenneth W. Jarvis 167 Keith Henney 169 A Loop-Operated Browning'Drake Receiver - - /. H. Gocfyl 171 A Simple A.C. Operated Tube Tester - - The Laboratory Staff 173 The Isotone Screen-Grid "Super"- Dudley Walford 174 "Radio Broadcast's" Service Data Sheets - - - - - - - 177 No. 15. The Bremer-Tully 8-10 Receiver No. 16. The Freshman Model Q Receiver Servicing Home-Made Radio Receivers - - - - B. B. A/corn 179 The Service Man's Corner ............. 181 Sound Motion Pictures ........ Carl Dreher 182 "Radio Broadcast's" Home Study Sheets - - - - - - - 183 No. 13. Calibrating a Radio Wavemeter No. 14. Plotting Power Tube Characteristics As the Broadcaster Sees It ....... Carl Dreher 185 An Inexpensive Audio Oscillator ..... Edward Stan^o 186 A Chart for Making DX Measurements - - James B. Friauf 188 Armchair Chats on Short- Wave Subjects - - Robert S. Kruse 189 "Our Readers Suggest — " ............. 192 New Apparatus and Its Applications - - 194 More Data on the Sargent-Rayment - - - Howard Barclay 197 Manufacturer's Booklets ........ 109 "Radio Broadcast's" Laboratory Information Sheets ..... 202 No. 149. A Resistance-Coupled Amplifier No. 153. Shielding No. 150. A Resistance-Coupled Amplifier No. 154. A.C. Tubes No. »ji. Moving-Coil Loud Speakers No. »jj. Band-Pass Circuits No. aji. Audio Amplifiers No. 356. Power Output The contents of this magazine is indexed in The Redden' Guide to Periodical Literature, which is on file at all public libraries. AMONG OTHER THINGS. . . THE next—the February—issue of RADIO BROADCAST will appear figuratively in new clothes. A famous designer is at work on an attractive new cover which will make RADIO BROADCAST more easily recognizable when you try to pick it out of the mass of others on the newsstands. The text will be set in a type which is easier to read and which presents a more attractive appearance than the type we now use. For those who are interested in such things, the present type face is Cadmus and the new RADIO BROADCAST will be set in Bodoni. Bodoni is a decorative type also notable because it is "easy on the eyes." The contents is in for some improving at the same time and we shall ask you to await the February issue for a com- plete announcement of that. TELEVISION occupies a good part of radio discussion these days and we want to be sure that our attitude on the subject is clear. "Television," unfortunately, means one thing to one man and something altogether different to the next. Television, like radio broadcasting, may be considered experi- mentally or in respect to its entertainment value—something the general public will find satisfactory. Television of entertain- ment value is certainly not here and is not in prospect for some little time. Articles in this magazine have outlined the difficulties to be overcome before "program television" can be attained. On the other hand, experimental television is here. What most people mean when they say the word now is merely experimen- tal television. We do not intend to fill this magazine with arti- cles on the subject when there isn't much to say, but we shall not fail to give those who are interested in experimenting with it as much useful information as we can. We certainly do not discourage experimenting, but in television it should be made perfectly clear that such it now is, and that on a limited scale. NO NEW feature we have added to RADIO BROADCAST in the six years of its history has created anything like the favorable response that the special pages for the radio service man have produced. Many interesting manuscripts have been received and we hope that others who also have ideas which should be set down on paper and sent on for our consideration will become suddenly ambitious and send us their contributions. THE present issue contains a wide selection of articles of interest: Boyd Phelps on "Unscrambling Television," Joseph Morgan on dynamic speakers, K. W. Jarvis on receiver performance, the Laboratory Staff on an a.c. operated tube tester, "The Service Man's Corner," Carl Dreher on "Sound Motion Pictures," and "Photographic Data for Broadcasters," Kruse on short-wave topics, the push-pull a.c. P. A. amplifier, are some of the most important. We are proud to offer these articles for they are all exclusive, interesting, and accurate to the last degree. TJEBRUARY RADIO BROADCAST will contain, among other 17 things, an article by Dr. L. M. Hull on "Overall Measure- ments on Broadcast Receivers," a striking story by Boyd Phelps on how amateur television has been accomplished, a remarkable story by the Labaratory on the value of filtering in audio am- plifiers, several valuable experimental articles on short-wave work and—a host of other features. — WILLIS KINGSLEY WING. OOUBLEDAT, OORAN & COMPACT, INC., Garden Qixy, MAGAZINES COUNTRY LIFE WORLD'S Won* THE AMERICAN HOME RADIO BROADCAST SHORT STORIES LE PETIT JOURNAL EL Eco FRONTIER STORIES WBrr THE AMERICAN SKETCH BOOK SHOPS (Book, of all Publisher,) I LORD it TAYLOR; JAMES MCCREBRY it COMPANY i PENNSYLVANIA TERMINAL AND 166 WEST 32ND ST. NEW YORK: < 848 MADISON AVE. AND 51 EAST 44111 STREET I 410 AND 526 AND 819 LEXINGTON AVENUE ( GRAND CENTRAL TERMINAL AND 38 WALL STREET CHICAGO: 75 EAST ADAMS STREET ST. Louis: 113 N. STH ST. AND 4914 MARYLAND AVE. KANSAS CITY: 920 GRAND AVE. AND 206 WEST 47TH ST. CLEVELAND: HIOBEE COMPANY SPRINGFIELD, MASS: MEEKINS, PACKARD & WHEAT OFFICES GARDEN CITY, N. Y. NEW YORK: 244 MADISON AVENUE BOSTON: PARK SQUARE BUILDING CHICAGO: PEOPLES GAS BUILDING SANTA BARBARA, CAL. LONDON: WM. HEINEMANN, LTD. OFFICERS F. N. DOUBLEDAY, Chairman of the Board NELSON DOUBLEDAY, President GEORGE H. DORAN, I'ice-President S. A. EVERITT, Vice-President RUSSELL DOUBLEDAY, Secretary JOHN J. HESSIAN, Treasurer LILLIAN A. COMSTOCK, Aisft Secretary TORONTO. DOUBLEDAY. DORAN » GUNDY, LTD. L. J. MCNAUGHTON, Atstt Treasurer CopTfigkl, 1929, m the United Stata, Newfoundland, Great Britain, Canada, and other countries by Doubleday, Doran & Company, Inc. All righli reiervcd. TERMS: $4.00 a year; single copies J5 cents. 154